function openWindow(url,width,height){
    if (!width) { width = 600; }
    if (!height){ height = 400; }
    
    var topPos = screen.height/2-height/2
    var leftPos = screen.width/2-width/2
    var win_cfg = "status=no,scrollbars=yes,location=no,resizable=yes,top="+topPos+",left="+leftPos+",width=" + width + ",height=" + height;
   	var win = window.open(url, "_NEW_WIN_" + window.name,win_cfg);
    win.focus() ;
}